If you happen across a pond full of croaking green frogs, listen carefully. Some of them may be lying.

A croak is how male green frogs tell other frogs how big they are. The bigger the male, the deeper the croak. The sound of a big male is enough to scare off other males from challenging him for his territory.

While most croaks are honest, some are not. Some small males lower their voices to make themselves sound bigger. Their big-bodied croaks intimidate frogs that would beat them in a fair fight.

(…)

…[B]iologists have long puzzled over deception. Dishonesty should undermine trust between animals. Why, for example, do green frogs keep believing that a big croak means a big male? New research is offering some answers: Natural selection can favor a mix of truth and lies, particularly when an animal has a big audience. From one listener to the next, honesty may not be the best policy.

(…)

By the mid-1900s, scientists had documented deception in cases where one species fooled another. Some nonpoisonous butterflies, for example, evolved the same wing patterns that poisonous species used to warn off birds. Within a species, however, honesty usually prevailed. Animals gave each other alarm calls to warn of predators; males signaled their prowess in fighting; babies let their parents know they were hungry. Honesty benefited both the sender and the receiver.

“The point of signaling was to get information across,” Dr. Nowicki said. “Deception was almost not an issue.”

There was just one hole in this happy arrangement: it presented a great opportunity for liars. Shrikes, for example, regularly use alarm calls to warn one another of predators. But sometimes the birds will use false alarm calls to scare other shrikes away from food.

Imagine that a shrike fools other shrikes with a false alarm. It eats more, and therefore may hatch more babies. Meanwhile, the gullible, less-nourished shrikes hatch fewer babies. If false alarms become common, natural selection should favor shrikes that are not fooled by them.

When scientists created mathematical models of this theory, they found that dishonesty could undermine many vital kinds of communication. The challenge, then, was to find out how honesty countered the advantage of deception. “The liars ought to be able to take advantage of the system, so that you’d have selection on the listeners to ignore the signals,” said Jonathan Rowell, a postdoctoral researcher at the University of Tennessee.

I found this last point particularly interesting: Does natural selection weed out gullibility, or just breed better and better liars? And does intraspecies deception take a toll on the entire species (i.e., favoring the less fit, undermining the integrity and trustworthiness of vital signals)?

Of course, it’s very tempting to extrapolate to the human world, where deception is practically a way of life. There is certainly ample evidence that deception has severely damaged the well-being of the United States, but I’m not sure there’s as much evidence that gullibility is being selected out. Yes, the Republicans got spanked in November, but only after the mess their lies created had grown to such epic proportions that it could no longer be concealed or spun. Unfortunately, I think we still have a long ways to go, and probably not a lot of time to get there.

In conclusion, I leave you with this tasty little morsel:

Dr. Ellner’s rough translation of their call: “I’m looking for female frogs, and if you come on my lily pad, I’ll show you a good time.”

No specific point to make here, but the NYT’s medicine writer-doctor has a nice roundup of all the progress we’ve made in the last fifty years since Eisenhower’s physician advised Mamie to snuggle with him in bed to keep him warm after his heart attack. (I would think you’d have to be very careful about who you gave advice like that to. “Don’t panic, Ms. Jolie; just calm down and do exactly as I say and I promise everything will be fine…”)